title: Protein synthesis rate is not suppressed in rat heart during senescence.
abstract: The purpose of these experiments was to determine whether mixed protein synthesis rates in hearts of Fischer 344 rats were decreased from maturity to senescence. When compared with 12-mo-old rat hearts, hearts from 23- to 25-mo-old rats had 13% lower concentrations of noncollagen protein, 9% less non-collagen protein per heart, 10% higher ratio of heart wet weight-to-body weight, and no difference in the basal rate of mixed protein synthesis, when expressed as fractional rate per day. Despite the 9% decrease in total noncollagen protein in 23- to 25-mo-old rat hearts, the derived value for milligrams protein synthesized per day was not different between age groups. When triiodothyronine was given for 3 days to mature and senescent rats, fractional rates of mixed protein synthesis were increased by similar percents (57-70%) in hearts from these two age groups. Basal and triiodothyronine-stimulated RNA concentrations in hearts of 12-mo-old and 23- to 25-mo-old rats were not different. These observations showed no decrease in either the basal or the maximal thyroid-stimulated rates of mixed protein synthesis in the hearts between mature and senescent rats. Thus an aging-programmed downregulation of mixed protein synthesis rates within cardiac muscle did not occur in the senescent Fischer 344 rat heart in this study.
authors.affiliation: Department of Physiology and Cell Biology, University of Texas Medical School, Houston 77225.
authors.forename: R B
authors.initials: RB
authors.lastname: Biggs
authors.forename: F W
authors.initials: FW
authors.lastname: Booth
mesh_terms: D000375:Aging / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D004285:Dogs; D006321:Heart / Q000033:anatomy & histology; D009124:Muscle Proteins / Q000096:biosynthesis*; D009206:Myocardium / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D011916:Rats, Inbred F344; D014284:Triiodothyronine / Q000097:blood / Q000494:pharmacology
chemical_list: D009124:Muscle Proteins; D014284:Triiodothyronine